AJP - Endocrinology and Metabolism, Vol 254, Issue 3 E384-E388, Copyright © 1988 by American Physiological Society
Episodic release of insulin by rat pancreas: effects of CNS and state of satiety
R. H. Safarik, R. M. Joy and D. L. Curry
Department of Physiological Sciences School of Veterinary Medicine University of California, Davis 95616.
This study reports that insulin is secreted in an episodic manner in rats
and that the characteristics of its release can be modified by the central
nervous system (CNS) and state of satiety. The pancreata of male
Sprague-Dawley rats were perfused using the in situ brain-pancreas
technique under urethan anesthesia. Episodic insulin release under
non-fasted conditions was not altered by the presence or absence of CNS
innervation to the pancreas. Under these conditions the interpeak period
was 5.9 and 6 min, respectively, and cycle length was 3.7 and 4 min.
However, perfusions that were performed following an overnight fast
demonstrated that the CNS is capable of modulating episodic insulin
release. After fasting, when comparing CNS-ablated with -intact
preparations, the period was shortened from 5.2 to 4.1 min (P less than
0.05), and the number of episodes per 90-min perfusion increased from 16.0
to 19.0 (P less than 0.05) when the pancreas was innervated by the CNS.
Additionally, the effect of fasting on denervated pancreata resulted in a
shortening of the cycle length, which was prevented when the CNS was
functional. These results demonstrate that episodic insulin release can be
modified by metabolic conditions and are subject to mediation by the CNS.
